I am a wedding photographer and currently my longest lens is the 70-200 f/2.8L IS II. I used to have a 5D2 and a 7D and during the ceremony I would put the 70-200 on the 7D which gave me about 320mm. I really never found myself needing much more reach than that. I recently sold both my cameras and bought two 5D3s. I love them but I have a feeling there will be several times this wedding season that I will be wishing I had the additional reach. The big problem I have found as that most telephoto lenses are very expensive being that I won't need it 95% of the time. I would love to have the new version of the 100-400 but who knows when that is going to come out and what it will cost. I was thinking about the 300mm f/4L and maybe getting the 1.4 extender just in case I need the extra reach. Any thoughts on a reasonably prices telephoto with IS that will get me the reach I need?